Study of Electronic Structures near Lattice Defects in Metals by the Measuretment of Electron Momentum Distributions

与离子晶体中的色心和硅晶体中的空位-氧络合物相比，金属晶格缺陷的电子结构还不够清楚。然而，最近的发展，在测量的二维角相关的湮灭辐射，使我们能够开始精确和现实的调查电子动量分布和电子波函数附近的金属和合金的晶格缺陷。本项目的目的是利用二维角关联机及其展开，研究晶格缺陷在倒易空间和真实的空间中的电子结构。（1）二维角相关机的扩展：利用专门设计的电子线路，成功地将128探测器系统扩展为256探测器系统。我们把计数率提高了四倍。(2)电子动量的测量 ...更多信息 纯铝和铝基稀合金中热平衡缺陷附近的分布：我们发现，在稀合金中，湮没辐射的多普勒展宽在熔点附近显示出异常的窄化。这种效应不能通过测量正电子寿命来观察。在2D-ACAR实验中，导出的自相关函数被解释为在中间温度范围内存在空位，但在熔点附近对应于正电子素的存在。由此，我们提出了一个nex正电子俘获模型。(3)氧化物高温超导体费米面的确定：为了研究氧缺陷对费米面的影响，我们进行了2D-ACAR实验。我们找不到任何效果。根据这个事实，我们又可以确定费米面。（4）对铅基稀合金中原子激子的直接观察;（5）对电子辐照镍中空位周围的电子动量分布进行了测量，并研究了氢对空位周围电子动量分布的影响。少

As compared with colour centers in ionic crystals and vacancy-oxygen complex in silicon crystals, the electronic structure of lattice defects in metals is not yet clear enough. However, recent developments in the measurement of two-dimensional angular correlation of annihilation radiations have allowed us to start precise and realistic investigations of electron momentum distributions and electron wavefunctions near lattice defects in metals and alloys. The purpose of the present project is to understand the electronic structure of lattice defects both in reciprocal space and in real space, by means of the two dimensional angular correlation machine and by their expansion. Results are summarized as follows;(1) The expansion of two-dimnsional angular correlation machin: we were successful in expanding the 128 detector system to the 256 detector systemby the use of specially designed electronic circuit. We raised the counting rate about four times.(2) The measurement of electron momentum … More distribution near thermal equilibrium defects in pure aluminum and aluminum based dilute alloys: We found that the Doppler broadening of annihilation radiations shows an abnormal narrowing near melting point in dilute alloys. This effect could not be observed by the measurement of positron lifetimes. In the 2D-ACAR experiment, the derived autocorrelation function is explained by the presence of vacancies in intermediate temperature range, but that near melting point corresponds to the presence of positroniums. From this fact, we proposed a nex positron trapping model.(3) The determination of Femi surface in oxide high temperature superconductors: In order to search the effect of oxygen deficiency, we did 2D-ACAR experiment. We cound not find any effect. From this fact, in turn, we can determine the Fermi surface. It was perfectly two-dimensional and one electron pillar and two kinds of hole pillars were found. (4) The direct observation of atomic excitons in lead based dilute alloys, and, (5) The measurement of electron momentum distribution around vacancies in electron irradiated nickel and the effect of hydrogens on it were performed. Less